Well I was having weird runway lighting behaviour post SU6 (not very bright or visible runways on approach, disappearing lighting as aircraft approaches and large blacked out/dark patches on the runways) mainly noticable at nighttime, and I think I’ve found the solution to my particular problem. I have Zinertek enhanced airport graphics installed. I removed the package, deleted rolling cache, rebooted FS and suddenly I had nice bright runways again with clear/working lighting. Good news is I installed Zinertek enhanced textures again and things are looking more normal now. This only happened after SU6 update to me and its taken a bit of game time for me to debug as it’s mainly noticable on nighttime approaches.